According to the provided text, what is the fundamental difference between birth and death, and why don't these concepts apply to avatars like Sai Baba?

Chapter 43 defines birth as the 'union of body and senses' and death as the 'separation of body and senses.' This cycle is presented as a fundamental aspect of existence. However, the text posits that these concepts are 'false imaginations' for enlightened beings who take avatars with the 'sole desire for the welfare of devotees.' Such beings, who can 'place their feet on the head of Time,' are not touched by birth and death in the conventional sense. Sai Baba is described as the Supreme Brahman, for whom the world is an illusion and consciousness of the body is absent. Therefore, the binding and loosening of the body and senses, which constitute birth and death for others, are irrelevant to his eternal nature.